The present invention relates to a surface finishing pad for use with a surface finishing machine such as a sander, burnisher or polisher.
Surface finishing machines are commonly used for sanding, burnishing or polishing wood, stone, metal or plastics surfaces. These machines typically contain a surface finishing pad which may be a sanding disc, a microfine finishing disc, buffing disc, or the like. In most instances, movement of the surface finishing pad is reciprocally driven by a motor which may have a backing plate fitted thereto so that the surface finishing pad can be operably attached to the backing plate. Known surface finishing machines may drive the surface finishing pad in a random orbital rotational motion, or a linear reciprocating motion.
For a given job the user of the surface finishing machine may require a range of surface finishing pads of different properties. Thus, in the case of a sanding job the user may need to use a range of surface finishing pads having sanding discs ranging from coarse through to very fine. This may require the user to spend a significant amount of time changing the surface finishing pads. It is known to attach surface finishing pads to a backing plate using an adhesive. It is also known to attach surface finishing pads to a backing plate using a hook and loop fastener such as VELCRO(trademark) which allows the pads to be interchanged. However depending on the job at hand, it is often found that when a hook and loop fastener is used the surface finishing pads tend to come loose or tear and/or the application of excess pressure can result in the pad moving with respect to, or coming loose from, the backing plate.
In many instances the user may also require surface finishing pads of different configuration or dimension depending on the job at hand. For this reason the user may have a number of machines having different shaped or sized backing plates.
At least one embodiment of the present invention provides a surface finishing pad which has a mounting pad onto which commercially available sanding discs or the like can be fitted and the mounting pad can be releasably attached to a backing plate of a surface finishing machine so that the mounting pad can be readily removed and replaced.
For the purposes of this specification the word xe2x80x9ccomprisingxe2x80x9d means xe2x80x9cincluding but not limited toxe2x80x9d, and the word xe2x80x9ccomprisesxe2x80x9d has a corresponding meaning. Also a reference within this specification to a document is not to be taken as an admission that the disclosure therein constitutes common general knowledge in Australia.
In a first aspect, the invention could be said to reside in a surface finishing pad for fitting to a base plate of a surface finishing machine, the surface finishing pad including a retaining disc for attachment to the base plate, the retaining disc containing engaging means for engaging a mounting pad onto which one or more surface finishing discs may be attached, said mounting pad including retaining disc engagement means complementary to the mounting pad engagement means, wherein an interference fit between the retaining disc and mounting pad engagement means provides for the mounting pad to be releasably fitted on to the retaining disc, such that, in use, the mounting pad is retained on the retaining disc.
In one form of the invention the retaining disc and mounting pad engagement means are complementary shaped peg and aperture wherein the dimensions of the aperture are slightly less than those of the peg so that the peg can be fitted into the aperture and can provide an interference fit therewith.
In the following discussion the invention will be described in respect of a retaining disc having a peg extending from one face and a mounting pad having a complementary aperture formed therein. However it will be appreciated that the invention also contemplates a surface finishing pad in which the retaining disc has an aperture into which a peg extending from a face of the mounting pad can be inserted so as to provide an interference fit therewith.
The peg and aperture may be circular, square or any other suitable shape. Preferably the peg and aperture are circular. In the case of a circular peg and aperture it may be necessary to also provide a rotation inhibition means to inhibit relative rotational movement between the retaining disc and the mounting pad. In the case of a square peg and aperture a rotation inhibition means will not normally be necessary because the square aperture will not allow rotation around the square peg.
The retaining disc may contain more than one peg extending from a surface thereof, and the mounting pad may have a corresponding number of complementary apertures formed therein such that the apertures in the mounting pad may be aligned with the pegs and then pushed over the pegs.
The mounting pad may be a laminate of two or more layers. In one specific form the mounting pad includes a first layer of resilient plastics for attachment to the retaining disc, a second layer of compressible material such as foam rubber, and a final layer of plastics onto which one or more surface finishing discs may be attached.
In one form of the invention the first layer of resilient plastics may be the only part of the mounting pad that forms an interference fit with the peg. Thus the aperture in the second and final layers may be of the same diameter or larger diameter than the peg, and the aperture in the first layer may be of slightly smaller diameter than the peg. This embodiment provides for ease of use in that it is only the relatively thin first layer that provides an interference fit and this therefore makes the mounting pad easier to fit than when the whole thickness of the mounting pad provides an interference fit with the peg.
Preferably the length of a peg extending from the surface of the retaining disc is less than or equivalent to the thickness of the mounting pad so that the peg does not protrude from a working surface of the mounting pad onto which the surface finishing discs are attached. It will be understood that when the first layer provides the primary interference fit with the peg the length of the peg need only be sufficient for the first layer to engage the peg.
The peg may be hollow so that a dust extraction means can be attached thereto and the hollow peg can act as a duct for removal of dust and the like from the surface as it is being finished. Suitable dust extraction means are known to those skilled in the art and are also discussed in PCT/AU00/00212. When dust extraction means are used it is preferable that the length of the peg is less than the thickness of the mounting pad. Thus, when a vacuum is applied the peg may provide a negative pressure so that the part of the mounting pad that extends past the peg may be influenced by the vacuum such that it assists in retaining the mounting pad on the retaining disc.
The peg may have a circumferential groove formed on an outer surface such that the diameter in the groove is about the same as the diameter of the aperture in the mounting pad. In this way the mounting pad may be snap fitted over the peg and into the groove in the peg. The width of the groove may be the same as or slightly greater than the thickness of the first layer of the mounting pad so that the first layer snap fits into the groove when the mounting pad is correctly fitted.
The peg may also be tapered outwardly from the surface of the retaining disc. The taper may be such that the diameter of the peg at the smaller diameter end adjacent the surface of the retaining disc may be about the same as the diameter of the aperture in the mounting pad, whilst the diameter of the peg at the larger end may be slightly greater than the diameter of the aperture so that the mounting pad can be fitted over the peg and the direction and angle of the taper can assist in forcing the mounting pad toward the retaining disc.
The surface finishing pad may be used on any standard surface finishing machine by fixing the retaining disc to the backing plate of the machine. Thus, the retaining disc and mounting pad may be sold together or separately and can be retrofitted to standard orbital sanding machines or the like. Alternatively, the surface finishing pad may be used on the surface finishing machine described in PCT/AU00/00212.
The surface finishing discs that are fitted onto the mounting pad may be any of the commercially available discs such as sanding discs, buffing discs and the like.
It will be appreciated that, in a second aspect, the invention also encompasses a surface finishing disc having the surface finishing pad of the first aspect of the invention attached thereto, and for use on a surface finishing machine having the retaining disc of the first aspect of the invention fitted thereto.
In a third aspect the invention could be said to reside in a surface finishing machine having the surface finishing pad of the first aspect of the invention fitted thereto.